Selector valve for a hydraulic circuit



May 28, 1968 PRlCE ET AL 3,385,170

SELECTOR VALVE FOR A HYDRAULIC CIRCUIT Filed Nov. 17, 1965 INVENTORRALPH E- PP/CE KURT A1- 655E.

ATTORN EY United States Patent 3,385 170 SELECTOR VALVE FOR A HYDRAULICCIRCUIT Ralph E. Price and Kurt M. Gebel, Wayneshoro, Pa., assignors toLandis Tool Company, Waynesboro, Pa. Filed Nov. 17, 1965, Ser. No.508,236 8 Claims. (Cl. 91-411) ABSTRACT OF THE DISCLOSURE The apparatusof this application relates to grinding machines in which a commonsupply of fluid under pressure is used to actuate both the traversemechanism and the feed mechanism. After a grinding wheel has beenadvanced to a position to begin a grinding operation, a valve is shiftedto disconnect the feed mechanism from the common supply prior toinitiating the traverse movement of the work relative to the grindingwheel. The valve which disconnects the feed mechanism from the supply offluid which continues to provide a traverse movement, acts to connectthe feed mechanism with a relatively low volume supply of fluid underpressure. The lower pressure and volume are sufficient to hold thegrinding wheel in grinding position and also to actuate the portion ofthe feed mechanism which acts through the hand wheel shaft to advancethe grinding wheel a short distance at a rate suitable for grinding.Thereafter, when the traverse mechanism is reversed, a momentaryincrease in pressure which normally occurs at the reversal point willnot be transmitted to the feed mechanism.

This invention relates to grinding machines, particularly those in whichthe grinding operation involves relative longitudinal and transversemovements between a workpiece and a grinding wheel.

In the normal operation of such machines, Where both longitudinal andtransverse movements are effected hydraulically, the hydraulic motorsfor effecting these movements are supplied with fluid under pressurefrom a common source. Since the longitudinal and transverse movementsnever occur simultaneously, this arrangement is inexpensive andsatisfactory. One characteristic of a common supply of fluid underpressure for longitudinal and transverse movements is that at thereversal point of the longitudinal movement, there is a momentarybuildup or impulse in the pressure in the system. This momentaryincrease in pressure occurs through the entire hydraulic systemincluding the means for effecting the transverse movement between theworkpiece and the grinding wheel. Ordinarily, this pressure impulse onthe transverse moving means is not objectionable. However, for workwhich requires very close tolerance, this pressure impulse on thegrinding wheel feed mechanism is objectionable because it may cause agrinding wheel to grind beyond the desired size.

It is, therefore, an object of the present invention to preventundesired relative transverse movement between a grinding wheel and aworkpiece at the reversal point of the longitudinal movement.

Another object is to disconnect the transverse moving means from thecommon supply of fluid under pressure after the grinding wheel has beenadvanced to operative position.

Another object is to provide means for disconnecting the transversemoving means from one source of fluid under pressure and connecting saidmeans to another source of fluid under pressure.

The drawing is a hydraulic diagram.

The means for causing the relative longitudinal movement between aworkpiece and a grinding wheel consists of a cylinder 10 attached towork carriage 11. Piston 12 slidably mounted in cylinder 10 is connectedthrough piston rods 13 and 14 and support members 15 and 16 to themachine bed 17.

The means for effecting the transverse movement consists of a cylinder30 in bed 17. Piston 31 is slidably mounted in cylinder 30. Piston 31has a piston rod 32 which, in turn, has a feed screw portion 35 withthreads engaging a worm wheel 36 in grinding wheel support 40. Wormwheel 36 is mounted at the lower end of vertical shaft 37 in wheelsupport 49. At the top of shaft 37, there is another Worm wheel 38 inoperative relation with worm gear 39. Worm gear 39 is part of shafthaving a hand wheel 46 mounted thereon. Shaft 45 also has a pinion 47 inoperative relation with rack 48. Rack 48 is also a piston rod for slowfeed piston 50 slidably mounted in cylinder 51.

The means for controlling the longitudinal movement consists essentiallyof a reversing valve and a start and stop valve 61 in valve housing 62.Start and stop valve 61 also performs the functions of cushioning thestart of the longitudinal movement and lay-passing the reversing valve60 when it is desired to effect the longitudinal movement manually. Anexhaust line B is connected to all points in the hydraulic systemrequiring drainage or eX- haust. The construction and operation of valve61 and the associated reversing valve 60 is described in detail in US.Patent 3,207,045, granted Sept. 21, 1965.

Operation The operation of the machine is initiated by energizing infeedsolenoid 1, shifting infeed valve 65 to the left and directing fluidunder pressure from pump #1 through the selector valve 66 and then tothe head end of rapid feed cylinder 30.

Rapid feed piston 31 advances the grinding wheel support 40 until saidpiston reaches the end of its stroke, i.e. when feed screw portion 35engages positive stop 42.

At this time, the exhaust pressure from the lower end of cylinder 30,which depends on the movement of piston 31, drops to zero. This pressurehas been holding valve 66 in the left-hand position and the valve 67 inthe righthand position.

Valve 67 is then shifted to the left by spring 68 and directs fluidunder pressure from pump #2 to the head end of slow feed cylinder 51 andalso to the left end of valve 66, shifting valve 66 to the right.

In its hand-hand position, valve 66 shuts off the supply of fluid underpressure from valve 65 to the head end of rapid feed cylinder 30, andconnects cylinder 30 with fluid under pressure from pump #2.

Since piston 31 is in its most advanced position, it requires only asmall volume of fluid to provide pressure to hold said piston and thegrinding wheel support 40 firmly in advanced position and to advance theslow feed piston 50.

Disconnecting feed cylinders 30 and 51 from pump #1 makes the feedmechanism free of fluctuations in pressure which occur during thetraverse movement of carriage 11, particularly at reversal.

After a grinding wheel has been placed in operative relation with aworkpiece, the traverse movement is started by shifting lever 70 to theleft and depressing valve 71. In this position, valve 71 connectspressure line 75 to direct fluid under pressure through throttle valve76 to the left hand end of start and stop valve 61 to start the traversemovement of carriage 11.

We claim:

1. In a grinding machine,

(a) a feed mechanism,

(b) a traverse motor,

(c) a common supply of fluid under pressure for actuating said feedmechanism and said traverse motor,

(d) a selector valve,

(e) and a valve operable when said feed mechanism is in advancedposition for shifting said selector valve to disconnect said feedmechanism from said common supply of fluid under pressure.

2. In a grinding machine,

(a) a feed mechanism,

(b) a traverse motor,

(c) a common supply of fiuid under pressure for actuating said feedmechanism and said traverse motor,

(d) means operable when said feed mechanism is in advanced position todisconnect said feed mechanism from said common supply of fluid underpressure,

(e) and means to connect said feed mechanism with an independent supplyof fluid under pressure to hold said feed mechanism firmly in advancedposition.

3. In a grinding machine,

(a) a feed mechanism,

(b) a traverse motor,

(c) a common supply of fluid under pressure for actuating said feedmechanism and said traverse motor,

(d) and means operable when said feed mechanism is in advanced positionto disconnect said feed mechanism from said common supply of fluid underpressure,

(e) the means for disconnecting said feed mechanism from said commonsupply of fluid under pressure also connecting said feed mechanism witha supply of fluid under pressure separate from said common supply offluid under pressure.

4. In a grinding machine,

(a) a feed mechanism,

(b) a traverse motor,

(c) a common supply of fluid under pressure for actuating said feedmechanism and said traverse motor,

(d) and means operable when said feed mechanism is in advanced positionto disconnect said feed mechanism from said common supply of fluid underpressure,

(e) the means for disconnecting said feed mechanism from said commonsupply of fluid under pressure maintaining operative relation betweensaid common supply of fluid under pressure and said traverse motor.

5. In a grinding machine,

(a) a feed mechanism,

(b) a traverse motor,

(c) a common supply of fluid under pressure for actuating said feedmechanism and said traverse motor,

(d) and means operable when said feed mechanism is in advanced positionto disconnect said feed mechanism from said common supply of fluid underpressure,

(e) and a valve operable in one position to connect said feed mechanismwith said common supply of fluid under pressure and in another positionto con- 4 nect said feed mechanism with another supply of fluid underpressure.

6. In a grinding machine,

(a) a feed mechanism,

(b) a traverse motor,

(c) a common supply of fluid under pressure for actuating said feedmechanism and said traverse motor,

(d) and means operable when said feed mechanism is in advanced positionto disconnect said feed mechanism from said common supply of fluid underpressure,

(e) the means for disconnecting said feed mechanism from said commonsupply of fluid under pressure being a valve operable in one position toconnect said feed mechanism and said traverse motor with said commonsupply of fluid under pressure and in another position to connect saidfeed mechanism with another supply of fluid under pressure whilemaintaining the connection between said common supply of fluid underpressure and said traverse motor.

7. In a grinding machine,

(a) a feed mechanism,

(b) a traverse motor,

(c) a common supply of fluid under pressure for actuating said feedmechanism and said traverse motor,

(d) means to prevent the operation of said traverse motor from adverselyaffecting said feed mechanism comprising means operable when said feedmechanism reaches advanced position to disconnect said feed mechanismfrom said common supply of fluid under pressure.

8. In a grinding machine,

(a) a feed mechanism,

(b) a traverse motor,

(c) a common supply of fluid under pressure for actuating said feedmechanism and said traverse motor,

(d) and means operable when said feed mechanism is in advanced positionto disconnect said feed mechanism from said common supply of fluid underpressure,

(e) the means for disconnecting said feed mechanism from the commonsupply of fluid under pressure being a valve actuated by exhaustpressure from said feed mechanism and normally held by said exhaustpressure in position to connect both the feed mechanism and the traversemotor to said common supply of fluid under pressure.

References Cited UNITED STATES PATENTS 2,103,530 12/1937 Henry 60-52 X2,277,640 3/1942 Harrington 60-97 X 2,659,204 11/1953 Conway et al.60-52 EDGAR W. GEOGHEGAN, Primary Examiner.

